(133 days)
The Gold Standard Diagnostics Borrelia burgdorferi IgM ELISA Test Kit is intended as a qualitative test for the detection of IgM antibodies to B. burgdorferi sensu stricto in human serum from symptomatic patients or people suspected of infection. When used as the first-tier screening test, positive and equivocal results must be supplemented through additional testing by one of the following methods:
· Standard two-tier test methodology (STTT) using an IgM blot test following current interpretation guidelines, OR
• Modified two-tier test methodology (MTTT) using the Gold Standard Diagnostics Borrelia burgdorferi VlsE-OspC IgG/ IgM ELISA Test.
The assay can also be used as a second-tier confirmation test using the MTTT methodology when used with the Gold Standard Diagnostics Borrelia burgdorferi VlsE-OspC IgG/IgM ELISA Test as the first-tier screening test.
Positive test results by either the STTT or MTTT methodology are supportive evidence for the presence of antibodies and exposure to Borrelia burgdorferi, the cause of Lyme disease. A diagnosis of Lyme disease should be made based on the presence of Borrelia burgdorferi antibodies, history, symptoms, and other laboratory findings.
The kit includes 12 x 8 well Antigen Coated strips. Conjugate. Substrate, Stop Solution, Wash Buffer, Diluent, Negative Control, Positive Control, and Cutoff Control. The controls are provided to determine if the assay is functioning properly and to determine the antibody level. The reagents are sufficient for 96 determinations.
During the test procedure, antibodies to B. burgdorferi (sensu stricto) if present in the human serum sample will bind to the antigens coated onto the wells forming antigen-antibody complexes. Excess antibodies are removed by washing. A conjugate of goat anti-human IgM antibodies conjugated with horseradish peroxidase is then added, which binds to the antigenantibody complexes. Excess conjugate is removed by washing. This is followed by the addition of a chromogenic substrate, tetramethylbenzidine (TMB). If specific antibodies to the antigen are present in the patients' serum, a blue color will develop. The enzymatic reaction is then stopped with a stopping solution causing the contents of the well to turn yellow. The wells are read photometrically with a microplate reader at 450nm.
The antigens used in the Gold Standard Diagnostics Borrelia burgdorferi IgM ELISA Test kit is a combination of B. burgdorferi sensu stricto strain B31 lysate, B. burgdorferi sensu stricto strain 2591 lysate, and a recombinant VlsE from B. burgdorferi sensu stricto strain B31. The lysates use spirochetes growing in BSK-H complete medium until mid-exponential phase. The recombinant VlsE protein is produced in E. coli SURE2 cells and purified by affinity chromatography. The purity of each antigen is assayed by SDS-PAGE followed by Coomassie staining and/or Western blotting.
Here's an analysis of the provided text to extract the acceptance criteria and study details for the Gold Standard Diagnostics Borrelia burgdorferi IgM ELISA Test Kit.
It's important to note that this document describes an In Vitro Diagnostic (IVD) device, not an AI/ML-based medical device. Therefore, many of the typical acceptance criteria and study designs associated with AI/ML, such as MRMC studies, expert adjudication, separate training/test sets with established ground truth protocols, and specific ground truth types (pathology, outcomes data, expert consensus), are not applicable or described in the same manner.
Instead, the acceptance criteria for IVDs typically revolve around analytical performance (sensitivity, specificity, precision, reproducibility, cross-reactivity, interference) and clinical concordance with a predicate device or clinical diagnosis.
Acceptance Criteria and Device Performance (IVD Device)
1. Table of Acceptance Criteria and Reported Device Performance
Since this is an IVD device, not an AI/ML device, the acceptance criteria are generally based on meeting certain performance metrics (e.g., specificity, sensitivity, precision, agreement with a predicate device) that demonstrate its substantial equivalence to a legally marketed device. The document does not explicitly state numerical acceptance thresholds for each metric, but rather presents the performance observed and implies that these results were deemed acceptable for market clearance.
Here's a table summarizing the reported device performance, which implicitly represents the met acceptance criteria for this IVD:
| Metric (Implicit Acceptance Criteria) | Reported Device Performance (Gold Standard Diagnostics Borrelia burgdorferi IgM ELISA) | Context/Notes |
|---|---|---|
| Primary Comparison (STTT) | Comparison with predicate device Trinity Biotech MarDx Borrelia burgdorferi EIA IgM Test Kit (K894293) for Standard Two-Tier Test (STTT) methodology. | |
| Positive Percent Agreement (PPA) | 90.3% (93/103) with 95% CI (82.9% - 95.5%) | Against the Predicate IgM ELISA from prospective samples. |
| Negative Percent Agreement (NPA) | 99.6% (460/462) with 95% CI (98.5% - 99.9%) | Against the Predicate IgM ELISA from prospective samples. |
| Second-Tier PPA (against IgM blot) | 98.3% (58/59) with 95% CI (90.9% - 99.9%) | When Gold Standard Diagnostics Borrelia burgdorferi IgM ELISA Test positive/equivocal samples were re-tested with an FDA-cleared IgM blot assay (as the second-tier for STTT). |
| Clinical Sensitivity (STTT) | Early: 75.9% (44/58) | |
| Disseminated: 100.0% (17/17) | ||
| Late: 89.7% (35/39) | Compared to predicate IgM ELISA in clinically characterized samples. | |
| CDC Panel Agreement (STTT) | Healthy: 93.0% | |
| Early Lyme: 76.7% | ||
| Cardiac Lyme: 66.7% | ||
| Neurological Lyme: 100.0% | ||
| Late: 85.0% | ||
| Look-alike disease: 81.1% | Agreement with clinical diagnosis for CDC panel. | |
| Analytical Specificity | Endemic Region: 96.1% | |
| Non-endemic Region: 90.5% | Determined by testing 208 asymptomatic individuals. | |
| Precision (Within-lab) | CV ranges from 1.3% to 13.3% depending on sample and parameter (SD or CV) | For various control and sample types across 12 days, duplicates per day. Lowest CV (positive control, SD) 1.3%, highest CV (negative sample, SD) 13.3%. |
| Reproducibility (Multi-site) | CV ranges from 2.5% to 18.6% depending on sample and parameter (SD or CV) | For various control and sample types tested at 3 sites, triplicates, twice per day for 5 days. Lowest CV (moderate positive, between run) 2.5%, highest CV (negative sample, total) 18.6%. |
| Cross Reactivity | Varies by condition (e.g., Tick-borne Relapsing Fever: 0% positive, Ehrlichiosis: 60% positive) | Some cross-reactivity noted for certain conditions (Ehrlichiosis, Babesiosis, Leptospirosis, Varicella Zoster Virus). This is expected for serological assays and acknowledged by the need for second-tier testing. |
| Interfering Substances | None detected performance effect for tested substances (Albumin, Bilirubin, Cholesterol, Hemoglobin, Triglycerides) | Tested at recommended concentrations; no effect on performance. |
| Secondary Comparison (MTTT) | Comparison of Modified Two-Tier Test (MTTT) methodology (using this device + VlsE-OspC IgG/IgM ELISA) against Standard Two-Tier Test (STTT) using the predicate IgM blot. | |
| Positive Percent Agreement (PPA) | 100.0% with 95% CI (83.2% - 100.0%) | For overall MTTT vs. STTT results for all prospective samples. |
| Negative Percent Agreement (NPA) | 95.7% with 95% CI (93.4% - 97.3%) | For overall MTTT vs. STTT results for all prospective samples. |
| Clinical Sensitivity (MTTT) | Early: 62.9% (39/62) | |
| Disseminated: 100.0% (22/22) | ||
| Late: 82.9% (34/41) | Compared to predicate STTT-IgM in clinically characterized samples. Notably higher for Late Lyme than predicate STTT-IgM (82.9% vs 22.0%). | |
| CDC Panel Agreement (MTTT) | Healthy: 100.0% | |
| Early Lyme: 76.7% | ||
| Cardiac Lyme: 66.7% | ||
| Neurological Lyme: 100.0% | ||
| Late: 80.0% | ||
| Look-alike disease: 96.7% | Agreement with clinical diagnosis for CDC panel. Notably higher for Late Lyme than predicate STTT-IgM (80.0% vs 35.0%) and for Look-alike Disease (96.7% vs 97.8%). |
2. Sample Sampled Used for the Test Set and Data Provenance
- Determination of Assay Cutoff: 208 normal sera (103 from endemic region, 105 from non-endemic region). Provenance not explicitly stated but implies a mix of endemic/non-endemic populations, likely within the US.
- Precision (Test Set): A panel of 4 samples (negative, high negative, low positive, moderate positive) + kit controls. Tested in-house.
- Reproducibility (Test Set): A panel of 4 samples (negative, high negative, low positive, moderate positive) + kit controls. Tested at three different sites.
- Analytical Specificity (Test Set): 208 asymptomatic individuals' samples from endemic and non-endemic regions.
- Cross Reactivity (Test Set): 277 samples from serum vendors, confirmed positive for specific markers (e.g., Tick-borne Relapsing Fever IgM, Treponemal Infections, etc.).
- Interfering Substances (Test Set): 3 samples (high negative, equivocal, low positive) spiked with interferents.
- Clinical Studies (Comparison with Predicate Device - STTT):
- Prospective Samples: 531 serum samples.
- Provenance: Collected from three sites (one internal, two external reference laboratories) "using prospective samples submitted for Lyme serology testing". This implies real-world, prospectively collected, likely US-based clinical samples.
- Clinical Studies (Sensitivity Study - STTT): 114 clinically characterized samples (early, disseminated, late stages of Lyme disease). Provenance not explicitly stated.
- Clinical Studies (CDC Panel - STTT): 280 positive and negative specimens from the Center of Disease Control (CDC). These are a characterized reference panel. Provenance is CDC, likely multi-site or pooled.
- Clinical Studies (Method Comparison – MTTT IgM, Prospective Study):
- Prospective Samples: 481 serum samples for the initial screening. 68 positive and equivocal samples carried forward for second-tier testing.
- Provenance: Collected from three sites (one internal, two external reference laboratories) "using prospective samples submitted for Lyme serology testing". Implies real-world, prospectively collected, likely US-based clinical samples.
- Clinical Studies (Sensitivity Study - MTTT): 125 clinically characterized samples (early, disseminated, late stages of Lyme disease). Provenance not explicitly stated.
- Clinical Studies (CDC Reference Panel - MTTT): 280 positive and negative specimens from the Centers of Disease Control (CDC).
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications
For IVD devices like this one, ground truth is typically established by:
- Consensus of clinical diagnosis for disease stages (clinically characterized samples).
- Confirmed status from reference laboratories or biological repositories (e.g., CDC panel, serum vendors for cross-reactivity).
- Comparison to a legally marketed predicate device (as done for the main comparative studies).
The document does not specify a number of experts or their qualifications for establishing ground truth for the test set. Ground truth is derived from the established clinical status of the samples (e.g., clinically characterized samples, CDC panel, confirmed positive from serum vendors). This is standard for IVD submissions, where the "ground truth" often relies on a combination of patient history, symptoms, other laboratory findings, and established reference panels or predicate device results, rather than a panel of independent human readers interpreting medical images.
4. Adjudication Method for the Test Set
Not applicable in the usual sense for an IVD kit. There's no human "reader" adjudication described. The "adjudication" is inherent in the established clinical status of the samples used as ground truth or the comparison to a predicate device. For instances where samples were "clinically characterized," this implies a clinical diagnosis that served as the reference standard, rather than an adjudication process of human interpretations of imaging/data.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance
Not Applicable. This is an IVD (laboratory diagnostic test kit), not an AI/ML-based medical imaging and interpretation device. MRMC studies are used for evaluating AI/ML systems that assist human readers in tasks like image interpretation.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done
Yes, in essence. The performance metrics (PPA, NPA, sensitivity, specificity, etc.) presented in the tables are the standalone performance of the Gold Standard Diagnostics Borrelia burgdorferi IgM ELISA Test Kit itself, analogous to an "algorithm only" performance for an IVD. There is no "human-in-the-loop" component for the performance of this diagnostic test kit once it is run according to its instructions. The interpretation of the overall Lyme disease diagnosis, however, is intended to be made by a clinician based on multiple factors, as stated in the Indications for Use.
7. The Type of Ground Truth Used (expert consensus, pathology, outcomes data, etc)
The ground truth for this IVD was established using a combination of:
- Clinical Diagnosis / Clinically Characterized Samples: For the "Sensitivity Study" and "CDC Panel," samples were derived from patients with known clinical diagnoses of Lyme disease stages (early, disseminated, late) or from healthy individuals.
- Reference Panels: Specifically, the CDC Panel which consists of "positive and negative specimens... for Lyme disease detection" that are "masked characterized serum panel." This implies a very high confidence in the true status of these samples.
- Confirmed Status from Vendors: For the "Cross Reactivity" study, samples were "obtained from serum vendors who confirmed their positivity for each respective marker."
- Predicate Device/Established Methodology: For the "Comparison with Predicate Device" and "MTTT Comparison" studies, the performance was measured against results obtained from a legally marketed predicate device (Trinity Biotech MarDx Borrelia burgdorferi EIA IgM Test Kit) or an established "Standard two-tier test methodology (STTT)" using the predicate IgM blot test. While the predicate is not "ground truth" in the pathological sense, it serves as the reference standard for substantial equivalence studies for IVDs.
8. The Sample Size for the Training Set
Not applicable for this type of IVD device. This is a laboratory immunoassay kit, not an AI/ML algorithm that undergoes a distinct "training" phase with a large dataset. The "training" in the context of IVD development would be the R&D and optimization process to develop the assay components and parameters (e.g., antigen formulation, antibody concentrations, incubation times, cutoff determination), which are iterative and not typically reported as a "training set" size in an FDA submission. The determination of the assay cutoff involved 208 normal sera, which could be considered part of the assay's "calibration" or optimization, but not a "training set" in the sense of supervised machine learning.
9. How the Ground Truth for the Training Set was Established
Not applicable. As explained in point 8, there isn't a "training set" in the AI/ML context for this IVD device. The assay development and cutoff determination process is a different methodology. The "ground truth" for establishing the assay cutoff was based on 208 normal sera (from endemic and non-endemic regions) and a subsequent ROC analysis to optimize sensitivity and specificity.
§ 866.3830
Treponema pallidum treponemal test reagents.(a)
Identification. Treponema pallidum treponemal test reagents are devices that consist of the antigens, antisera and all control reagents (standardized reagents with which test results are compared) which are derived from treponemal sources and that are used in the fluorescent treponemal antibody absorption test (FTA-ABS), theTreponema pallidum immobilization test (T.P.I.), and other treponemal tests used to identify antibodies toTreponema pallidum directly from infecting treponemal organisms in serum. The identification aids in the diagnosis of syphilis caused by bacteria belonging to the genusTreponema and provides epidemiological information on syphilis.(b)
Classification. Class II (performance standards).